Solenoid plunger stop



Sept. 3, 1968 R. w. FLENTGE SOLENOID PLUNGER STOP Filed Oct. 1l, 1966 I N VEN T02 P055?? A( /fZf/vraf MM6M AT1-Ys.

United States Patent C 3,400,351 SOLENOID PLUNGER STOP Robert W. Flentge, Roselle, Ill., assignor to Albert F. Dormeyer, Chicago, Ill. Filed Oct. 11, 1966, Ser. No. 585,880 9 Claims. (Cl. 335-257) ABSTRACT F THE DISCLOSURE Solenoid having a plunger and plug and a plunger stop for cushioning the plunger during seating and for providing a positive predetermined air gap between the plunger and plug in seated position.

This invention relates in general to a solenoid, and more particularly to a improved solenoid plunger stop that greatly increases the life of a .solenoid by cushioning the plunger when it moves from protracted to seated position. Further, where the solenoid is provided with a plug, the improved plunger stop provides the necessary assurance of a given air gap to minimize residual buildup between the plunger and plug when the plunger is in seated position.

S-olenoids having solenoid plunger stops have been well known, and heretofore many solenoids have been designed with devices to cushion the plunger during move- -rnent from protracted to seated position. But all such devices have required complex mounting arrangements and have ben expensive and even impractical for certain solenoids.

The present invention relates to an improved solenoid plunger stop that is especially useful for solenoids of the pull-type disclosed in my copending application Ser. No. 440,826, filed Mar. 18, 1965, now Patent No. 3,303,445.

The solenoid plunger stop :of the present invention includes a pair of rigid outer annular members usually called washers having a resilient intermediate annular member sandwiched there-between and all of which are received and locked into place on the outer free end of the solenoid plunger and which coact with a part of the solenoid to cushioningly stop the plunger when it moves ywith considerable force to seated position following energization of the coil. The washers are mounted on the plunger by slightly diametrically reducing the size of the plunger at the youter end to define a shoulder against which one of the outer washers may abut, and for convenience locking the Washers in place against the shoulder through a C-type retaining clip engaging in a groove formed in the plunger and engaging against the other of the outer washers. The outer washers are of rigid material such as metal, but may be of magnetic or non-magnetic metal, while the intermediate washer is of a resilient material such as rubber or the like.

Accordingly, it is an object of the present invention to provide a solenoid of the pull-type having a plunger stop cushioning against the closing forces, wherein the plunger stop may be inexpensively manufactured and assembled on the plunger, and will greatly increase the life of the solenoid.

Another object of the present invention is in the provision of a plunger stop for a solenoid plunger that includes a resilient washed sandwiched between a pair of rigid washers and fixed in position along a plunger to coact with a part of the solenoid mounting and cushion against closing forces when the plunger moves from protracted to seated position.

Still another object of the present invention is to provide a plunger stop for the solenoid plunger of a solenoid where the plunger mates with a plug when the plunger 3,400,351 Patented Sept. 3, 1968 ICC is in seated position, and where the plunger stop cushions the solenoid against the closing vforces of the plunger and assures a given air gap between the plunger and plug to minimize residual build-up and to also preclude bottom` ing of the plunger on the plug.

Other objects, features and advantages of the invention `will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheet of drawing, wherein like reference numerals refer to like parts, in which:

FIG. l is an axial sectional View taken through a solenoid having the solenoid plunger stop according to the present invention and showing some parts broken away for purposes of clarity;

FIG. 2 is an exploded view of the solenoid of FIG. 1;

FIG. 3 is an enlarged fragmentary view of a part of the plunger and showing the plunger stop construction in section according to the present invention;

FIG. 4 is a transverse sectional view taken substantially along line 4--4 of FIG. 1; and

FIG. 5 is a transverse sectional view taken substantially along line 5 5 of FIG. 1.

Referring now to the drawings, the solenoid illustrated is of a pull-type that is employed to be mounted in fixed position so that the plunger can apply a pulling force to a member to be actuated. It should be further appreciated that the present invention may be employed on other types of solenoids Where it is desired to cushion the plunger against closing forces, and that the solenoid illustrated i.s Imerely a type that can effectively employ the plunger stop of the present invention to enhance its life.

The solenoid generally includes a coil tube 10 of nonmagnetic material, a plug 11 of magnetic material, a face plate 12 of magnetic material, a plunger 13 of magnetic material, a coil 14 having electrical leads 15, and a cover or casing member 16. While the plunger stop of the present invention is shown as used on a tubular solenoid, it should be appreciated that it could well be used on other types of solenoids.

The coil tube 10 is in the form of a cylindrical sleeve which is at one end telescopically received over a cylindrical portion 17 of the plug 11. The tube is abutted against a shoulder 18 formed by a radial flange 19 at the outer end of the plug, and an annular groove 20 is formed in the cylindrical portion 17 so that staking 21 fixes the coil tube 10 onto the plug 11.

The other end of the coil tube is telcscopically received within a bore 22 formed in the face plate 12. An annular relieved portion or beveled portion 23 is formed at the outer end of the face plate 12 and directly along the outer end of the bore 22 so that the outer end of the coil tube 10 may be flared at 24 to prevent movement of the face plate 12 oli the end of the coil tube.

Insulating tape 25 is wound over the coil tube 10` and coacts with insulating lwashers 26, 26` arranged against the shoulder 18 of the plug 11 and the radial end face 27 of the face plate 12 to define an insulati've surface against which the coil turns of the coil 14 may be wound. It should also be appreciated that the coil tube, plug and end face thereby define a bobbin for the coil 14.

The plug flange 19 is annularly notched at one end to define a shoulder 28 against which the cover member 16 abuts when arranged in position over the coil 14. An annular groove 29 is formed in the face plate 12 `so that staking 30 may be performed on the casing 16 to secure the casing in position. A lattened portion 31 is also provided on the face plate 12 so that the end of the cover member 16 may be deformed to preclude possible rotation of the casing relative to the face plate.

The outer end of the face plate 12 is `diametrically reduced and threaded at 32 to receive a nut 33 thereon that coacts with a shoulder 34 to sandwich therebetween a fixed panel or bracket 35 which is apertured at 36 to receive the reduced portion of the face plate. Thus, the solenoid is mounted to a panel or bracket 35 by the face plate 12.

The inner end of the plunger 13 is conically fonmed a 37 to enter into a conical recess 38 -formed in the adjacent end of the plug 11. A plunger stop 39, which comprises the present invention, is mounted on the outer free end of the plunger 13 and coacts with the face plate 12 to hold the conically-shaped end 37 of the plunger 13 in slightly spaced relation from the plug recess 38 4when the plunger is completely closed and in seated position. While not shown, it shouuld be appreciated that the mating ends of the plunger and plug may be otherwise shaped than shown. For example, the ends may be llat where the end `faces would be in radial planes, or they may be angular or inclined in a different fashion than that shown. Moreover, the plunger stop 39 cushions the plunger against the closing forces and transmits the closing only to the face plate 12, all of which greatly increase the life of the solenoid. The outer end of the plunger 13 is ibifurcated at 40 and provided with a transverse hole 41 to Ifacilitate connection of the plunger to a `member to be actuated. While the plunger is cylindrical and formed with bifurcated and conical ends, it should be appreciated that it could take other shapes and still utilize the plunger stop of the present invention.

The plunger stop 39 includes a pair of annular members or washers 42, 42 of rigid material having arranged therebetween an annular member or washer 43 of resilient material. The washers 42 are preferably of metal, but may be of magnetic or non-magnetic material, while the washer 43 is preferably of rubber, plastic or the like. The `Washers 42 and 43 are substantially identical in size, and are provided with bores 42a and 43a therethrough of equal size whereby the washers are snugly received on a idiametrically reduced portion 44 formed on the outer end of the plunger. The inner iwasher 42 abuts against a shoulder 4S formed by the reduced portion 44. An annular groove 46 is formed in the 'diametrically reduced portion 44 to receive a C-:shaped retaining ring or clip 47 that holds the washers 42 and 43 on a portion 44a of the reduced portion 44. The portion 44a has an axial length substantially equal to the combined axial width of the washers 42 and 43. Thus, the retaining ring 47 iixes the Washers 42 and 43 on the plunger and against axial movement therealong except on the portion 44a, and against radial movement.

In the operation, when the solenoid plunger 13 is drawn from protracted to closed and seated position, the plunger stop 39 serves to stop the plunger 4from allowing the inner conical end 37 to seat against the conical recess 38 of the plug thereby maintaining a given gap between the plunger and plug to minimize residual buildup. Further, during the closing of the' plunger, the inner ring or washer 42 engages against the outer end of the face plate 12 and transmits a force against the resilient washer 43 which because of its fixed position absorbs the force to effectively cushion the plunger during the seating thereof. A slight movement of the innermost washer 42 rwill take place during closing of the plunger, and this movement is in the ldirection of the outermost or backup washer 42 and the retaining ring 47, whereby the innermost or protective washer 42 will move axially along the diametrical portion 44a of the plunger. Cushioning of the plunger greatly increases the life of the solenoid by a substantial amount. That the intermediate resilient Iwasher is sandwiched `substantially fbet-ween the outer rigid washers serves to protect and prolong its life. Further, the washers 42 and 43 are of substantially uniform thickness. And since the washers 42 are sized substantially identical to the resilient washer 43 and are substantially radially positioned on the plunger, the retaining ring 47 is substantially radially positioned on the plunger and the washer 42 adjacent the face plate 12 seats against the end of the face plate which is also subsatntially radially arranged, -forces transmitted to the resilient Washer are substantially uniform over the entire dimension thereof.

It will be understood that moditications and variations may be eEected without 'departing from the scope of the novel concepts of the present inventino, but it is understood that this application is to be limited only by the scope of the appended claims.

The invention is hereby claimed as follows:

1. A solenoid comprising a coil tube having a coil thereover, a plug secured at one end of said -coil tu'be, a face plate for mounting of said solenoid secured at the other end of said coil tube, a plunger slidably received in said tube and movable toward said plug upon energization of said coil, and means on said plunger cushioning said plunger against said face plate during energization of said coil and keeping said plunger in slightly spaced relation from said plug when in seated position, said means being fixed against movement along the plunger and including a pair of annular members of rigid material and an annular member of resilient material therebetween.

2. A solenoid as dened in claim 1, wherein said rigid annular members are of magnetic material.

3. A solenoid as delined in claim 2, wherein said rigid annular members are of non-magnetic material.

4. A solenoid as dened in claim 1, wherein said rigi annular members are of metal and said resilient annular member is of rubber.

5. A solenoid as delined in claim 1, wherein said plunger includes a 'stepped portion `delining a shoulder at the outer free end and an annular groove adjacent thereto, and wherein said cushioning means includes a resilient Washer arranged between a pair of rigid washers all arranged against said shoulder, `and a retaining clip is mounted in said groove to hold the washers in fixed relation along the plunger.

6. A solenoid as defined in claim 1, and means on the face plate for mounting said solenoid on an `apertured panel.

7. A solenoid as defined in claim 1, wherein said annular members extend substantially radially of said plunger.

l3. A plunger stop for a pull-type solenoid having a plunger, said plunger stop comprising a resilient washer sandwiched between a pair of rigid washers all fixed on said plunger and mounted on the plunger so that the rigid washer striking the solenoid in seated position is movable along the plunger against said resilient washer.

9. A plunger stop as dened in claim 8, wherein the rigid and resilient washers are of substantially the saine radial dimensions.

References Cited UNITED STATES PATENTS 1,229,294 6/ 1917 `Kuntz 335-255 XR, 2,104,399 1/1938 Kuhn `335--255 2,651,744 9/ 1953 Acklin et al 335-262 XR 3,207,961 9/1965 Lohr 335-255 BERNARD A. GILHEANY, Primm-y Examiner.

GEORGE HARRIS, Assistant Examiner.

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, D.C. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,400 ,351 September 3 1968 Robert W. Flentge It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 20, after "closing" insert forces line 42, after "EI-shape" insert spring Column 4, line 13, "inventino" should read invention Signed and sealed this 17th day of February 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. 5 E.

Attesting Officer Commissioner of Patents 

